Individuals who were hospitalized for bronchiolitis during infancy subsequently developed asthma 2 to 3 times more frequently than their normal cohort. This effect was observed whether infantile bronchiolitis was caused by RS virus or another agent. The basis for this increased risk of asthma is not understood. BIBLIOGRAPHIC REFERENCES: Chanock, R. M., Kim, H. W., Brandt, C. D., and Parrott, R. H.: Respiratory syncytial virus. In Evans, A. S. (Ed.): Viral Infections of Man: Epidemiology and Control. New York, Plenum Publishing, 1977, pp. 365-382. Chanock, R. M., Richardson, L. S., Belshe, R. B., Kim, H. W., and Parrott, R. H.: Prospects for prevention of bronchiolitis caused by respiratory syncytial virus. Pediatr. Res. 11: 264-267, 1977.